Why do software Companies do this?

I'm learning the Mac version of Dxo V4.1.1. I want to output to a custom size 4"x6". There are five preset sizes,all in centimeters, none of what I want.
Page 65 of the manual says use the dropdown menu in the size dialog box and choose custom. You can specify the size in inches or centimeters.

There is no option for custom size. I send DXO support an email asking where is the custom size option. I tell them I am using the Mac version.

There answer. That's a windows only feature. No timetable as yet for implementing the custom size option on the mac. Sorry for the confusion (No where does it state that the custom size option is Windows only).

That really stinks.!!!! Is it too much trouble to give both versions the same feature. Is it too much trouble to say it's a windows only version.

It's rediculous actions like this and other stupid things that make me think that software companies live by different rules than other companies of most other types of businesses and feel that they can get away with it.

John